1. Field of the Invention
The present invention relates to a safety plastic filler neck cap for an automobile, etc., and particularly to a screwed type filler neck cap that is developed for the purpose of providing a safety plastic filler neck cap capable of performing two functions. That is, to control the torque balance in screwing and to prevent fuel leakage from the filler neck port caused by the separation of the cap upon receiving an impact.
2. Description of the Prior Art
Fuel filler neck ports for automobiles, etc. which use latches and latching teeth for screwing torque (balance) control have been known widely. Conventionally, various types of structures have been provided for those filler neck port caps. However, many of such structural designs proposed are complicated, thus inviting a high cost for the filler neck caps with these structures. Furthermore, the fuel filler neck caps capable of preventing the leakage of gasoline from the filler neck ports have been proposed by, for example, U.S. Pat. No. 4,177,931. The mechanism used for preventing the fuel leakage in the foregoing filler neck caps is to keep the screw body itself intact from damage while only the upper portion of the screw body is left to be broken together with the filler neck cap cover upon receiving an impact. However, these are not satisfactory in structure as they are not reusable after being damaged. Up to now, it seems that the fuel filler neck caps provided with a structure allowing the cap cover alone to come off the screwing body portion of the cap have not been offered as yet.